One of the most critical and actual problem of civil aviation is the ice formation on aerodynamic surfaces while flying in supercooled clouds. This may result in significant degradation of aircraft performance. In the past this very often lead to serious and fatal accidents. The number of known world-wide accidents and serious incidents in which icing is believed to play a decisive role is on the order of several hundred and thus considerable.
European industry is particularly affected by icing hazards since it holds the largest worlds market share for turboprops, medium-sized jet aircraft and helicopters, categories that are more prone to ice related problems. The situation is even more critical since recently it has become obvious that the greatest icing hazard is due to cloud conditions with supercooled large drops (SLD). The diameter ranges up to several hundred micron and drops are then often referred to as freezing drizzle. The SLD are found in both a precipitating or a non-precipitating mode. In SLD-conditions ice accretion on the airframe might become extraordinary with accretion rates of up to 1 mm per minute.
The hazard of aircraft icing, in general, and those related to atmospheric conditions with SLD, in particular, were underestimated in the past. Civil authorities and airframe manufacturers paid insufficient attention to these unusual and admittedly rare situations. The main concern of airworthiness authorities is that icing hazard is not being reduced by all the new technologies, even with the newly certified aircraft. Current certification standard, therefore, might be not adequate, especially for turboprop aircraft and rotorcraft. It is the objective of the EURICE (European Research for aircraft Ice CErtification) project to improve our knowledge of hazardous icing conditions which are outside the common knowledge. Especially outside those atmospheric conditions documented in FAA 25 and 29, Appendix C. The further intention of EURICE is to draw conclusions for aircraft certification.
The EURICE project is a two years project and is partially funded by the Directorate General VII for Transport of the European Commission. Twelve partners from universities, research organisations, industries, aviation authorities are collaborating. Six countries are involved.
To achieve the objectives, EURICE will collect atmospheric data sets
from supercooled clouds where significant icing was either observed or
was likely to occur. For that purpose all available data from certification
flights and research flights in supercooled clouds will be put into a data-base.
A substantial part of the EURICE-project will be a flight campaign. Three aircraft will operate in three different European regions to gather more data from supercooled clouds with emphasis on SLD. The aircraft flight campaign will enlarge the data-base, will improve our capabilities in icing research and initiates a joint scientifically based European effort in aircraft icing research. Finally, a review and a critical analysis of current certification and operational requirements, means of compliance and operational procedures related to icing will be performed. It is attempted to identify new certification procedures and operational scenarios and to evaluate the impact on both design and certification cycle and operational procedures.